(a) Technical Field of the Invention
The present invention relates to a fire door lock, and in particular to a fire door lock comprising a movable seat, which when actuated and moved by a handle bar, moves first and second slide blocks and a lock tongue inward to further drive first and second latch bars inwards to unlock the fire door, and which, when the door is closed and a tongue control plate is brought into contact with an external fixture and thus actuated, automatically returns to the original locked position to stretch the first and second latch bars outward to secure the fire door and also cause a tongue holder seat to abut against and maintain the tongue in the locked condition thereby realizing a three-directional locking of the fire door.
(b) Description of the Prior Art
Fire door locking mechanisms are known, such as Taiwan Patent Publication No. 568161, which discloses in FIG. 11 of the attached drawings thereof a central locking mechanism 3 and upper and lower locking mechanisms 4, 6 that are coupled to the central locking mechanism 3, and a transmission mechanism 9 that is coupled to the central locking mechanism 3 so that when an operating handle bar is depressed, the transmission mechanism 9 drives the central locking mechanism 3, which in turn drives the upper and lower locking mechanisms 4, 6 to operate in a simultaneous manner for locking and unlocking a fire door.
The conventional device, although effective in overcoming the drawback of other known fire door mechanism that no upper and lower vertical latching are included. However, such a conventional device does not include horizontal latching or locking so that when the fire door can be broken in by breaking a middle portion of the door. Thus, further improvement is needed.
Other prior art references, such as U.S. Pat. No. 7,144,050, suffer the same drawback.
Thus, it is desired to provide an improved fire door lock that enhances security of the fire door, while maintaining easy operation by a user to open the door.